Professional music app for iPad?

Hi all, I was wondering if there was a high-grade music app availble for the iPad. What I want to do is create my own beats on an iPad with loops. Also is there away to attach a microphone to an iPad at the moment?

I'm hoping that Apple will release a variation of GarageBand for the iPad.

In the meantime, I'm testing out Xewton Music Studio for the iPhone on my iPad. So far, so good, but since the dev doesn't have access to an iPad, he hasn't made the move to start developing for it yet.